1. Field of the Invention
The present invention relates to an image sensing apparatus for sensing a still image and/or moving image.
2. Description of the Related Art
Conventionally, image sensing apparatuses such as electronic cameras and the like, which record/play back still images and moving images sensed by a solid-state image sensing element such as a CCD or the like using memory cards having solid-state memory elements as recording media, have already been commercially available.
In such electronic camera, a single shot mode for sensing images frame by frame every time the shutter button is pressed, and a continuous shot mode for sensing images successively while the shutter button is held down can be switched by selecting either mode.
On the other hand, when an image is sensed using a solid-state image sensing element such as a CCD or the like, a dark noise correction process can be done by computations using dark image data which is read out after charge accumulation in the same manner as in actual image sensing while the image sensing element is not exposed, and actually sensed image data which is read out after charge accumulation while the image sensing element is exposed.
With this process, sensed image data can be corrected in terms of image quality deterioration such as pixel omission or the like caused by dark current noise produced by the image sensing element and small scratches unique to the image sensing element, thus obtaining a high-quality sensed image.
Especially, since dark current noise increases with increasing charge accumulation time and temperature rise of the image sensing element, if exposure for a long period of time (seconds) or at high temperature is done, a great image quality improvement effect can be obtained, and the dark noise correction process is a function effective for the electronic camera users.
However, in the conventional image sensing apparatus such as an electronic camera or the like, when actual image sensing is done after dark image data is sensed, the shutter release time lag becomes longer by the dark image sensing time in the single shot mode, thus missing a shutter chance.
On the other hand, when dark image data is sensed after actual image sensing, the image sensing interval between the first and second frames is prolonged by the dark image sensing time in the continuous shot mode. As a result, constant image sensing frame intervals cannot be set.
One aspect of the present invention is to provide an apparatus, which comprises an image sensing device, a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device having a first mode for making the image sensing device perform the first image sensing operation and then the second image sensing operation, and a second mode for making the image sensing device perform the second image sensing operation and then the first image sensing operation, and a storage device for storing signals obtained in the first and second modes processed by the signal processing device, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.
Another aspect of the present invention is to provide an apparatus, which comprises an image sensing device, a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device having a first mode for making the image sensing device perform the first image sensing operation and then the second image sensing operation, and a second mode for making the image sensing device perform the second image sensing operation and then the first image sensing operation, and a switching device for switching the signal processing device between the first and second modes in accordance with a state of shutter release operation, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.
Another aspect of the present invention is to provide an apparatus, which comprises an image sensing device, a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device having a first mode for making the image sensing device perform the first image sensing operation and then the second image sensing operation, and a second mode for making the image sensing device perform the second image sensing operation and then the first image sensing operation, and a switching device for switching the signal processing device to the first mode when the exposure start instruction device issues an exposure start instruction while the signal processing device is executing the second image sensing operation in the second mode, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.
Another aspect of the present invention is to provide an apparatus, which comprises an image sensing device, an exposure instruction device for issuing an exposure preparation instruction at a first stroke position of a shutter release member, and issuing an exposure start instruction at a second stroke position of the shutter release member, and a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device performing the second image sensing operation in response to the exposure preparation instruction issued by the exposure instruction device, and performing the first image sensing operation in response to the exposure start instruction issued by the exposure instruction device, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.